Road Blasters used an optical mechanical (mouse type) sensor, while Star Wars used POTs (analog joystick type), and mame emulates it like that (RB uses a DIAL, SW uses a AD_STICK) Also, RB didn't use the Y axis, unless someone hacked it to take the place of the foot pedal.
While they
look similar, the 1-axis optical steering wheel from Road Blasters will not easily convert to a 2-axis potentiometer yoke like Star Wars.
There are a number of yokes that you can use (or easily adapt) for Star Wars -- check out the list of (analog joystick) yoke games in the right column
here.
(definitely avoid Paperboy and Two Tigers yokes)
Scott